TITLE:   GCN CIRCULAR
NUMBER:  35637
SUBJECT: GRB 240125A: AstroSat CZTI detection of a short burst
DATE:    24/01/26 08:30:34 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

J.Joshi (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short-duration GRB 240125A which was also detected by Glowbug (C.C. Cheung, GCN Circ. 35630).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-01-25 09:35:00.35 UTC. The measured peak count rate associated with the burst is 287 (+139, -40) counts/s above the background in the combined data of three quadrants (out of four), with a total of 208 (+50, -50) counts. The local mean background count rate was 263 (+7, -10) counts/s. Using cumulative rates, we measure a T90 of 1.4 (+0.11, -0.47) s.

The source was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-01-23 09:34:58.75UTC. The measured peak count rate associated with the burst is 532 (+74, -81) counts/s above the background in the combined data of all quadrants, with a total of 1132 (+156, -172) counts. The local mean background count rate was 1587 (+5, -6) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb